| Najm ud-din Ali Khan | |
| Shuja-ul-Mulk (Hero of the Country) Nazam-ud-Daulah (Star of the State) Mahabat Jang (Horror in War) | |
| Succession: | Nawab of Bengal and Bihar |
| Reign: | 5 February 1765 – 8 May 1766 |
| Coronation: | 23 February 1765 |
| Birth Date: | ca. 1747 |
| Birth Place: | Delhi, Delhi Subah, Mughal Empire |
| Death Date: | 8 May 1766 (aged 19) |
| Death Place: | Murshidabad, Bengal, British India |
| Burial Place: | Jafarganj, West Bengal, India |
| Predecessor: | Mir Jafar |
| Successor: | Najabat Ali Khan |
| Dynasty: | Najafi |
| Father: | 2nd Son of Mir Jafar |
| Mother: | Munni Begum |
| Religion: | Shia Islam |
Najmuddin Ali Khan or Najm ud-din Ali Khan, better known as Najm-ud-Daulah (or Nazam-ud-Daulah) (ca. 1747– 8 May 1766), was the Nawab of Bengal and Bihar from 1765 to 1766. He was the second son of Mir Jafar.
Najm-ud-Daulah was crowned as the Nawab following the death of his father Mir Jafar. During his coronation he was only 15 years old. He ascended to the throne on February 5, 1765.
In 1765 after the victory in the Battle of Buxar the British had formally gained Dewani of Bengal and Bihar from Shah Alam II. The Nawab formally conferred this Dewani to the British on September 30, 1765.
Najmuddin died soon afterwards, on May 8, 1766, apparently from a fever caught at a formal party given at Murshidabad fort in honour of Robert Clive. He was buried at Jafraganj Cemetery and was succeeded by his younger brother Nawab Najabat Ali Khan.
Nazam-ud-Daulah was the son of Munni Begum (noble) and Mir Jafar.
Nazam-ud-Daulah was appointed as Mir Jafar's heir with the title of Murshidzada Bahadur, by Mir Jafar himself on 29 January 1764.
After the death of Mir Jafar Nawab Nazim Najm-ud-din Ali Khan succeeded him to the Nawab's throne under the titles of Shuja-ul-Mulk (Hero of the Country), Nazam-ud-Daulah (Star of the State) and Mahabat Jang (Horror in War) at the age of 15 on February 5, 1765; it was confirmed by the East India Company on February 23, 1765. This cost him £140,000 which was divided among the members of the Calcutta Council.
Nawab Nazim Najm-ud-din Ali Khan died on May 8, 1766, of fever he caught at a party, which was given in honour of Robert Clive. The Nawab was buried at Jafarganj Cemetery on the west of his father, Mir Jafar's grave. The Nawab was childless. Najabat Ali Khan, Nazim-ud-din's brother, according to Mohammedan law was the right successor of the late Nawab, on the throne. Thus, Najim-ud-din was succeeded by his brother as Nawab Nazim Najabat Ali Khan.